The Syrian army on Thursday began a staged withdrawal of troops and vehicles from the Castello Road in Aleppo, the head of Russian military in Syria said.

RIA news agency cited Vladimir Savchenko as saying the Syrian government had done so to ensure the delivery of humanitarian supplies into rebel-held east Aleppo.

The Pentagon, however, said it had no intelligence to indicate the withdrawal had begun.

The Syrian Observatory for Human Rights, a UK-based activist group, meanwhile, said the Syrian army had started to withdraw, only to be replaced by Russian troops.

Zakaria Malahifji, of the Aleppo-based rebel group Fastaqim, rejected the Russian statement. "There is no withdrawal by the regime from the Castello Road," he told the Reuters news agency.

Savchenko said opposition forces were yet to pull back from the road.

The delivery of humanitarian aid is a key part of a US-Russia ceasefire deal in effect since Monday.

The UN has accused the Syrian government of refusing to allow its aid deliveries into the stricken city.

About 20 trucks loaded with aid remained in a buffer zone between Turkey and Syria on Thursday, awaiting a green light from Damascus to begin their journey to Aleppo.

A screengrab of drone footage of eastern Aleppo provided by Russia

The Russian defence ministry meanwhile created a "live webcast" of the situation in Aleppo, including the aerial monitoring of eastern Aleppo by drone flights.

The ministry's website said the footage would "provide transparency of ceasefire regime implementation in the Syrian Arab Republic by the sides".

Some of the footage apparently showed a line of trucks waiting on a road clear of military vehicles. Middle East Eye cannot verify the footage as authentic.

Russia on Thursday also called for the UN Security Council to adopt a resolution endorsing the ceasefire deal.

Vitaly Churkin, the Russian ambassador, said there were discussions at the UN on the proposed resolution that could be adopted on Wednesday when the Security Council holds a special meeting on Syria.

"We are working on it," he said. "I think we need to adopt it on the 21st."

The US secretary of state, John Kerry, will join his Russian counterpart Sergei Lavrov at the meeting, to be held on the sidelines of the annual UN General Assembly meeting.

Churkin said the resolution would provide "endorsement of the agreement" reached last week that allowed a ceasefire to go into effect on Monday, paving the way to aid deliveries and a possible resumption of peace talks.

Addressing the council, US ambassador Samantha Power said that the deal was "not an agreement based on trust and promises".

"It is an agreement based on reciprocal actions, halting attacks and allowing for deliveries of assistance," she said.

Under the deal, the United States and Russia will set up a joint implementation centre to cooperate in the targeting of rebels considered "terrorist" by both sides. President Bashar al-Assad's government will ground its planes and helicopters.

"The regime would no longer be able to use the excuse that it is targeting (the al-Qaeda-linked) al-Nusra in order to go after its own people," Power said.

More than 300,000 people have been killed in the five-and-a-half-year war in Syria where UN peace efforts have failed to unite the many players in the conflict behind a political settlement.